Divers off the Pembrokeshire coast may be about to re-write history after discovering an unidentified shipwreck.

Until now it was widely believed that no ships were lost when the French invaded Fishguard in 1797 - the last foreign invasion of mainland Britain.

But items found off Strumble Head appear to be from a large warship dating back to the Napoleonic era.

Sub-aqua club members have discovered copper drift pins, large pieces of iron, a swivel gun and three cannons.

Strumble Head has a legendary reputation for wrecking trading ships and is just as dangerous today as it was hundreds of years ago

Richard Hughes

The finds have sparked interest from a number of official bodies, including the historic buildings agency Cadw.

The wreck, which lies in 30m (98ft) of water, was found by chance last year by Richard and Rebecca Hughes of Merlin's Bridge, near Haverfordwest.

Because of strong currents and poor weather they and other members of the Fishguard Sub-Aqua Club were unable to return to the site until this summer.

After several false starts they eventually located the wreck and over the course of several dives have started to get an idea of the importance of their discovery.

Mr Hughes, the club's diving officer, said: "Strumble Head has a legendary reputation for wrecking trading ships and is just as dangerous today as it was hundreds of years ago.

Poor visibility

"Conditions for diving are rarely favourable so expeditions to this area have to be carefully planned.

Two the keel pins recovered next to a two litre bottle for size comparison

"Underwater visibility is often very poor so with no surface light at times we can only see what is visible in the beams of our torches.

"The day we first discovered the wreck visibility was unusually good, otherwise we would never have found it."

Club members have been able to recover a few small items from the sea floor including copper drift pins.

The Government's Receiver of Wreck has appointed the club as the official guardian of the site and the small finds to date have been donated to St Mary's Church Hall in Fishguard as part of the Last Invasion exhibition of artefacts.

According to legend, the 1797 invasion was repelled by Jemima Nicholas and other local women dressed in Welsh costume who were mistaken from a distance by the French as British troops.

The Welsh assembly's historic monuments agency Cadw and the Nautical Archaeological Society are hoping to send specialist divers to find out more about the wreck next year.

A spokeswoman for Cadw said: "Cadw is hoping to arrange for divers to explore the wreck early next year."